initial sync*, part of #221

lib/src/js/printer.dart

Index: lib/src/js/printer.dart
diff --git a/lib/src/js/printer.dart b/lib/src/js/printer.dart
index d5cf9e1ef54845859a3778df3d0eb7b2198985de..c545073f2e25bbdc7321f2312f70e550795e9f8b 100644
--- a/lib/src/js/printer.dart
+++ b/lib/src/js/printer.dart
@@ -509,6 +509,7 @@ class Printer implements NodeVisitor {
 
   void functionOut(Fun fun, Node name) {
     out("function");
+    if (fun.isGenerator) out("*");
     if (name != null) {
       out(" ");
       // Name must be a [Decl]. Therefore only test for primary expressions.
@@ -770,6 +771,12 @@ class Printer implements NodeVisitor {
 
   visitSpread(Spread unary) => visitPrefix(unary);
 
+  visitYield(Yield yield) {
+    out(yield.star ? "yield* " : "yield ");
+    visitNestedExpression(yield.value, yield.precedenceLevel,
+        newInForInit: inForInit, newAtStatementBegin: false);
+  }
+
   visitPostfix(Postfix postfix) {
     visitNestedExpression(postfix.argument, LEFT_HAND_SIDE,
                           newInForInit: inForInit,
@@ -1032,6 +1039,8 @@ class Printer implements NodeVisitor {
       out('get ');
     } else if (node.isSetter) {
       out('set ');
+    } else if (node.function.isGenerator) {
+      out('*');
     }
     propertyNameOut(node.name, inMethod: true);